Is there a servo torque calculator? I need a servo that can lift a 1-foot long leg weighing 1 pound.
First you will need to determine how the weight is distributed along the length of the leg. Googling terms like "calculate beam torque" might provide ueful info.
If your 1 foot long leg is of an evenly distributed mass along its length then its centre of gravity will be half-way along the beam.
Torque therefore is 1lb x 0.5ft or 0.5lbft or 6lbin.
To convert into metric units simply use the relevant conversion factors of 1lb = 454gm and 1inch = 2.54cm.
Hence 0.5lbft = 6lbin = 6919gmcm = 6.919kgcm
and to make it truly metric bring in gravity where force = mass x acceleration or Newtons = kg x 9.81m/s/s
hence your 0.5lbft = 6.919 x 9.81 / 100 = 0.679 NM (Newton Metres)